Designing Robust Superhydrophobic Materials for Inhibiting Nucleation of Clathrate Hydrates by Imitating Glass Sponges

Superhydrophobic surfaces are suggested to deal with hydrate blockage because they can greatly reduce adhesion with the formed hydrates. However, they may promote the formation of fresh hydrate nuclei by inducing an orderly arrangement of water molecules, further aggravating hydrate blockage and meanwhile suffering from their fragile surfaces. Here, inspired by glass sponges, we report a robust anti-hydrate-nucleation superhydrophobic three-dimensional (3D) porous skeleton, perfectly resolving the conflict between inhibiting hydrate nucleation and superhydrophobicity. The high specific area of the 3D porous skeleton ensures an increase in terminal hydroxyl (inhibitory groups) content without damaging the superhydrophobicity, achieving the inhibition to fresh hydrates and antiadhesion to formed hydrates. Molecular dynamics simulation results indicate that terminal hydroxyls on a superhydrophobic surface can inhibit the formation of hydrate cages by disordering the arrangement of water molecules. And experimental data prove that the induction time of hydrate formation was prolonged by 84.4% and the hydrate adhesive force was reduced by 98.7%. Furthermore, this porous skeleton still maintains excellent inhibition and antiadhesion properties even after erosion for 4 h at 1500 rpm. Therefore, this research paves the way toward developing novel materials applied in the oil and gas industry, carbon capture and storage, etc.

(defined as t 0 ) and when the temperature (defined as t n ) began to rise immediately. The induction time 26 (t i ) was t n -t 0 , and the subcooling was ΔT = T n -T 0 . Temperature stability was regarded as a sign that 27 the system had stabilized. If no hydrates were generated after 250 min, the induction time was 28 arbitrarily assigned as >250 min. As indicated in Figure 4a, around 30 induction time data points ( Figure   29 S5b) were collected to get the average value for each sample. The adhesion force between cyclopentane hydrate particles with different samples were measured by 30 the MMF device. As shown in Figure S4b, the MMF consisted of Zeiss(S100) inverted optical microscope, 31 manual micromanipulator and remote mechanical micromanipulators, a temperature control system 32 (Huber CC1-K20, Germany) and an image processing system. The adhesive force recording device was 33 connected to the camera via the microscope. The cold tank was constructed with aluminum cooling 34 jacket, which was used to control the temperature of the test system. tank.
(2) Water droplets were placed onto the ends of glass fibers and submerged in liquid nitrogen 37 until frozen, then the ice particle was fastened on the moveable cantilever. Immerse the moveable 38 cantilever into cyclopentane (3.2 °C) holding for 1h to prepare CP hydrate particles.
(3) the sample was 39 fixed on the stationary cantilever, then put it into cyclopentane (3.2 °C). (4) Move the moveable surface at a constant velocity until it detached from the sample surface. Based on 40 repeated tests, Figure S8 shown the displacement (Δx) of CP hydrate with different samples under the same 3 experimental circumstances. Stainless steel had the greatest displacement, followed by Ni Foam, were submerged in the sediment fluid, which was stirred with speed of 1500 rpm to accelerate scouring.

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To prove the erosion resistance of the P(HHIP)@SiO 2 @Ni foam, the scratch test (knife scraping) was 25 conducted, as shown in Supplementary Video 2. The surface of P(HHIP)@SiO 2 @Ni foam (110ppi with a 26 size of 1 cm×2.5 cm×0.13 cm) was scraped at least 80 times with a knife. After the test, the water 27 drops could roll off the abrasion surface without residues, no water drops pinned into its surface. The 28 wettability of the abrased samples was characterized as shown in Figure S10a.

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To further prove the mechanical robustness of the P(HHIP)@SiO 2 @Ni foam (110ppi with a size of 1 31 cm × 2.5 cm × 0.13 cm), the load sliding reciprocating friction testing was carried out, as shown in 32 Supplementary Video 3. A loading weight (50 g) on the surface of the P(HHIP)@SiO 2 @Ni foam was 33 ragged forward and backward as one cycle, repeatedly at least 60 times. The wettability of the abrased 34 samples was characterized as shown in Figure S10b.